Could anyone help me to solve the issue in the following code.

U =[0    0.0987         0         0    0.0767;
    0    0.0141         0         0    0.0184]

V =[0    0.2948         0         0    0.2310;
    0    0.4909         0         0    0.4257]
     

for v =1:size(V,2)
for u =1:size(U,1)
    A(u,v) =((U(u-1,v-1)).*(V(u,v)))-sum((V(1:u-1,v)).*(U(u-1,v-1)))
   
end
end

In this code the expression A(u,v) does not need to perform for first row but it needs to be performed for second row.

Coud anyone please help me to solve this.

[Adam]

Why not just start the u loop from 2 instead of 1 then?

[jaah navi]

Could you help me how to start u loop from 2.

[Adam]

How did you manage to get that far if you don't know how to start a for loop from 2?!

You explicitly start your for loop from 1, just replace that with a 2

for u =2:size(U,1)

    doc for

tells you more about for loops and how to specify them, but you seem to knnow this anyway, having written the code at the top!

[jaah navi]

I already tried with 2 but i get all the values to be zeros.

[Adam]

Just initialise

A = V;

before the loop as this appears to be the end result you want.

You should make it clear in the question what end result you want though. There is no reason for us to assume that you want the first row to be equal to that of V when you just say " does not need to perform for first row"

Answer 1

[Dvir Haberman]

As Adam pointed out in the comments section: it seems like you're accessing index 0 of a MATLAB array. Unlike C, Python and others array indices in MATLAB starts in 1.

You could precalculate the first element and start your for loop from 2.

To start you loops from 2 simply do

for v =2:size(V,2)

for u =2:size(U,1)

    A(u,v) =((U(u-1,v-1)).*(V(u,v)))-sum((V(1:u-1,v)).*(U(u-1,v-1)))

   

end

end

remember that you need to precalculate the first elements

[jaah navi]

i tried but unable to get the result.

What I actually need is the ouput should be as follows.

[ 0 0.2948 0 0 0.2310;

0 (0.4909-0.2948)*0.0987 0 0 (0.4257-0.2310)*0.0767].

[0 0.2948 0 0 0.2310;

0 0.0775 0 0 0.0149]

Could you please help me on this.

Answer 2

[Guillaume]

What I actually need is the ouput should be as follows:

[ 0     0.2948                                 0    0    0.2310;
0       (0.4909-0.2948)*0.0987      0    0    (0.4257-0.2310)*0.0767]

[0    0.2948    0    0    0.2310;
0    0.0775    0    0    0.0149]

Hum,

>> (0.4909-0.2948)*0.0987
ans =
     0.019355

not 0.0775.

Assuming the v-1 were a mistake and the offset was only on the rows, this is equivalent to the expression you wrote in your question and doesn't require loops:

A = [V(1, :); U(1:end-1, :) .* (V(2:end, :) - cumsum(V(1:end-1, :), 1))]